White balance adjusting device for a color video camera

Abstract

The present invention relates to a white balance adjusting device for a color video camera for photographing an object irradiated by light from a blackbody radiation source or a non-blackbody radiation source. When recording operation is being performed, the white balance adjusting device prevents the moving operation of a fluorescent light correction filter and a color temperature conversion filter into an optical path of image pickup means and permits a white balance adjustment operation performed by electrically correcting an output of the image pickup means. When a recording operation is not being performed, the white balance adjusting device permits the moving operation of the fluorescent light correction filter and the color temperature conversion filter into the optical path and permits white balance adjustment operation performed by electrically correcting the output of the image pickup means.

What is claimed is: 
     
       1. A white balance adjusting device for a color video camera, comprising: image pickup means for picking up an image of an object,   color measuring means for outputting color information corresponding to a color temperature of ambient light,   correction means for electrically correcting an output of said image pickup means based on the color information outputted from said color measuring means, thereby to perform a white balance adjustment,   optical filter means selectively interposable in an optical path of said image pickup mean and used for optically modifying light incident on said image pickup means,   drive means for moving said optical filter means into or from said optical path based on the color information,   recording state detection means for detecting whether the video camera is in a recording state or a non-recording state, and   control means for controlling said drive means and said correction means to forbid operation of said drive means and to permit operation of said correction means in response to detection of the recording state by said recording detection means, and to permit operation of said drive means and operation of said correction means in response to detection of the non-recording state by said recording detection means.   
     
     
       2. A white balance adjusting device for a color video camera for photographing an object irradiated by light from a blackbody radiation source or a non-blackbody radiation source, comprising: image pickup means for picking up an image of said object,   color measuring means for outputting color information corresponding to a color temperature of ambient light,   light source determination means for determining, based on the color information form said color measuring means, whether the source of the ambient light is the blackbody radiation source or the non-blackbody radiation source,   a non-blackbody radiation correction filter selectively interposable in an optical path of said image pickup means and used for optically modifying light incident on said image pickup means from said object irradiated by light from the non-blackbody radiation source,   drive means for moving said non-blackbody radiation correction filter into or from said optical path based on the color information,   correction means for electrically correcting an output of said image pickup means based on the color information outputted from said color measuring means and data of a correction amount corresponding to said non-blackbody radiation correction filter, thereby to perform a white balance adjustment, and   control means for controlling said drive means to cause said non-blackbody radiation correction filter to be moved into said optical path when it is determined by said light source determination means that said ambient light source is the non-blackbody radiation source, and to cause said non-blackbody radiation correction filter to be moved form said optical path when it is determined by said light source determination means that said ambient light source is the blackbody radiation source.   
     
     
       3. A white balance adjusting device for a color video camera in accordance with claim 2, wherein said non-blackbody radiation source includes a fluorescent lamp and said non-blackbody radiation correction filter includes a fluorescent light correction filter.   
     
     
       4. A white balance adjusting device for a color video camera for photographing an object irradiated by light from a blackbody radiation source or a non-blackbody radiation source, comprising: image pickup means for picking up an image of said object,   color measuring means for outputting color information corresponding to a color temperature of ambient light,   light source determination means for determining, based on the color information from said color measuring means, whether the source of the ambient light is the blackbody radiation source or the non-blackbody radiation source,   difference determination means for determining whether a difference between a reference color temperature for said image pickup means and the color temperature of the ambient light exceeds a prescribed value or not,   a non-blackbody radiation correction filter selectively interposable in an optical path of said image pickup means and used for optically modifying light incident on said image pickup means from said object irradiated by light from the non-blackbody radiation source,   a color temperature conversion filter selectively interposable in said optical path of said image pickup means for optically converting light incident on said image pickup means from said object irradiated by light from the blackbody radiation source to light having the reference color temperature,   non-blackbody radiation correction filter drive means for moving said non-blackbody radiation correction filter into or from said optical path based on said color information,   color temperature conversion filter drive means for moving said color temperature conversion filter into or from said optical path,   correction means for electrically correcting an output of said image pickup means based on the color information outputted from said color measuring means, data of a correction amount corresponding to said non-blackbody radiation correction filter, and data of a correction amount corresponding to said color temperature conversion filter, thereby to perform a white balance adjustment, and   control means for controlling said non-blackbody radiation correction filter drive means to cause said non-blackbody radiation correction filter to be moved into said optical path when it is determined by said light source determination means that said ambient light source is the non-blackbody radiation source, and to cause said non-blackbody radiation correction filter to be moved from said optical path when it is determined by said light source determination means that said ambient light source is the blackbody radiation source, and controlling said color temperature conversion filter drive means to cause said color temperature conversion filter to be moved into said optical path when it is determined by said difference determination means that the difference between the reference color temperature for said image pickup means and the color temperature of the ambient light exceeds said prescribed value, and to cause said color temperature conversion filter to be moved from said optical path when it is determined by said difference determination means that said difference does not exceed said prescribed value.   
     
     
       5. A white balance adjusting device for a color video camera in accordance with claim 4, wherein said non-blackbody radiation source includes a fluorescent lamp and said non-blackbody radiation correction filter includes a fluorescent light correction filter.   
     
     
       6. A white balance adjusting device for a color video camera in accordance with claim 4, further comprising: an iris diaphragm for adjusting an amount of light incident on said image pickup means,   aperture control means for controlling an aperture opening of said iris diaphragm based on a level of a luminance component contained in the output of said image pickup means, and   correction value output means for calculating an exposure correction value corresponding to the color information outputted from said color measuring means when said determination means determines that said light source is not the blackbody radiation source, and outputting the exposure correction value to said aperture control means as a signal for correcting the aperture opening by an amount corresponding to the exposure correction value.   
     
     
       7. A white balance adjusting device for a color video camera in accordance with claim 6, wherein said correction value output means comprises means for calculating an exposure correction value based on the color information outputted from said color measuring means and a spectral transmittance characteristic of said non-blackbody radiation correction filter, thereby to output the calculated exposure correction value to said aperture control means as a signal for correcting the aperture opening by an amount corresponding to the calculated exposure correction value.   
     
     
       8. A white balance adjusting device for a color video camera in accordance with claim 6, wherein said color measuring means comprises a spectrum sensor for measuring the intensity of incident light by separating the incident light into three wavelength components of red, green and blue,   said light source determination means comprising means for determining whether said ambient light source is the blackbody radiation source or the non-blackbody radiation source, based on a relationship between a first ratio of a specified one of the three wavelength components to a second wavelength component of the three wavelength components, and a second ratio of the specified wavelength component to a third wavelength component of the three wavelength components, and   said correction value output means comprises means for outputting an exposure correction value corresponding to said relationship.   
     
     
       9. A white balance adjusting device for a video camera for photographing an object irradiated by light from a blackbody radiation source or a non-blackbody radiation source, comprising: image pickup means for picking up image of said object,   color measuring means for outputting color information corresponding to a color temperature of ambient light,   light source determination means for determining, based on the color information from said color measuring means, whether the source of said ambient light is the blackbody radiation source or the non-blackbody radiation source,   correction means for electrically correcting an output of said image pickup means based on the color information outputted from said color measuring means, thereby to perform a white balance adjustment,   an iris diaphragm for adjusting an amount of light incident on said image pickup means,   aperture control means for controlling an aperture opening of said iris diaphragm based on a level of a luminance component contained in the output of said image pickup means, and   correction value output means for calculating an exposure correction value corresponding to the color information outputted from said color measuring means when said determination means determines that said ambient light source is not the blackbody radiation source, and outputting the exposure correction value to said aperture control means as a signal for correcting the aperture opening by an amount corresponding to said exposure correction value.   
     
     
       10. A white balance adjusting device for a video camera in accordance with claim 9, wherein said color measuring means comprises a spectrum sensor for measuring the intensity of incident light by separating the incident light into three wavelength components of red, green and blue, and   said light source determination means comprises means for determining whether said ambient light source is the blackbody radiation source or the non-blackbody radiation source, based on a relationship between a first ratio of a specified one of the three wavelength components to a second wavelength component of the three wavelength components, and a second ratio of the specified wavelength component to a third wavelength component of the three wavelength components.   
     
     
       11. A white balance adjusting device for a color video camera for photographing an object irradiated by light from a black body radiation source or a fluorescent lamp, comprising: image pickup means for picking up an image of said object,   color measuring means for outputting color information corresponding to a color temperature of ambient light,   light source determination means for determining, based on the color information form said color measuring means, whether the source of the ambient light is the blackbody radiation source or the fluorescent lamp,   a fluorescent light correction filter selectively interposable in an optical path of said image pickup means and used for optically modifying light incident on said image pickup means from said object irradiated by light from the fluorescent lamp,   drive means for moving said fluorescent light correction filter into or from said optical path based on said color information,   correction means for electrically correcting an output of said image pickup means based on the color information outputted from said color measuring means and data of a correction amount corresponding to said fluorescent light correction filter, thereby to perform a white balance adjustment,   an iris diaphragm for adjusting an amount of light incident on said image pickup means,   aperture control means for controlling an aperture opening of said iris diaphragm based on a level of a luminance component contained in the output of said image pickup means, and   correction value output means for calculating an exposure correction value based on the color information outputted from said color measuring means and a spectral transmittance characteristic of said fluorescent light correction filter when said light source determination means determines that said light source is the fluorescent lamp, and outputting the exposure correction value to said aperture control means as a signal for correcting the aperture opening by an amount corresponding to the exposure correction value.